Fix a uninitialized memory error in reconstruction.
Fix a uninitialized memory error in reconstruction.

With this change, the elevator sequence now reconstructs with 0.2 pixel average
reprojection error. That's over about 2000 markers, 120 frames, and 25 tracks.
Reconstruction is now working for real!

Nazg-Gul/libmv,keir/libmv,keir/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv,keir/libmv,Nazg-Gul/libmv,keir/libmv